24 Hour Heat.
Do not use heat a night. Unless your house is dropping below the low 40's for many days at a time, absolutely no night heat should be given. Chameleons need the temperature high during the day to digest the food, but a low drop at night to absorb the nutrients from what they consume. Secondly, Ceramic Heat Emitters are known to dry out the air, and not be appropriate during the day as a basking heat because they do not emit light. Chameleons also respond to the point where more intense light is, to be the point where the higher heat will be. If you provide heat without light, then it will not be as effective.
Rubber Plant.
Ficus Elastica is toxic and not recommended for captive chameleons. It is a good plant in structure and keeps well, but because of its toxity, the similar Ficus benjamina should be opted for. A cage the size of yours deserve to have much larger and dense LIVE vegitation. 4' is a larger vertical space allowing you teo keep larger hibiscus, Ficus, Shefflera, as well as hang large vined pothos. You can check the Live Plant section of this website for info on plants and a few links to offsite chameleon-safe-plant articles.
Murcury Vapor.
Mercury Vapor Bulbs produce very high heat. You should recheck your basking spot temperature. Do not use an analogue dial thermometres. If you have any, you can basically trash those ones, they are almost always incorrect. Instead use Digtial thermometers. You can buy them with cords that are probes that work well.
Also, the MVBs produce a lot of UV which some people say can be problematic for some chameleons as it has been suggested that they need to regulate their temperature and their UV absorption, seperately.
High levels of UVA can actually blind people, proven by people who live in the north of Canada and the arctic from when the sun rebounds off of the reflective snow causing 'snowblind'. Chameleons, specifically Panthers are not hot desert reptiles and may not be adapted to handle this either.
I suggest trying a "Heat Bulb" that does not produce UV for a week and see if behaviour changes.